Actually, the standard narrow-band O2 sensor isn't really a mission critical sensor. If you unplug the O2 sensor, chances are you will get a check engine light, and your gas milage will suck, but the car will run just fine under WOT conditions.

 

I acutally have my rear os sesnor removed ALL the time as it is a gooid bung for my motec unit

I get one cel code and other than that my car works' 100%

No rich running or other issues seen

I dont have a cel bulb in the dash so I dont even notice it till I hook up my scan tool

 

The rear O2 sensor is even less mission critical. It is only there to check the operation of the cat.

 

So have we chocked the power loss issue up to a secondary fuel map switch, low octane gas (which seems impossible to me unless the car owner accidentally put 89 in the car as otherwise it would be misrepresenation on Sunoco's part and I doubt they'd let that happen), or some other factor?

 

Actually, I hate Sunoco pump gas. I filled up with 94 octane once and got horrible knock when the car was running great with Mobil 93 octane previously.

 

Wow, so if you get a CEL the car still runs fine? Honda is NOTHING like that, the dam car will not rev and has about 1/3 of the power. At least that is what my NSX did.

 

I know that BP here in atlanta REALLY sucked, I put a tank full in a new car with less then 30,000 miles and it started SMOKING really bad, whonose.

 

Ryanmcd2, Hondas are like that. My '00 Civic and '90 Accord both went into limp mode at the slightest hint of a sensor gone wrong.

 

I have the Dynoflash'd ECU in my Evo8, and it's been working great for me. From what I've been reading, some of you are beating a dead horse. Isn't this thread about a guy that made good power but lost some? I really do doubt that it's the programming in the Dynoflash. Evo ECU's are sensitive to ****ty gas, cuz from what I know, they run at and sometimes beyond the limit (knock). Why don't we wait and see what happens to that guy's car (the one in question) and see what happens on his next dyno session, with good gas.

I think you people need to stop rippin on Al and go try the Dynoflash. It's pretty obvious that he knows what he's doing if every car he's flashed is making good power, right?

My $0.02...

 

No problems here with mine! 287 whp and 298 torque bone stock !! Go Al !!

 

Most importantly I have the Dyno Flashed ECU in my car and its making close to 600 whp - BUT to get that HP figure it requires C-16 118 octane leaded race fuel. On 94 octane pump gas the most power I can make is about 380 to the wheels. So you can see that your fuel OCTANE is a serious limit to how much power any given engine can safely make. When we tune customers cars they are ALL tuned to ZERO knock activity - period. WE DON'T use knock sensitivity attenuation like some of our compeitition does becuase we want the factory knock protection feature to work and we want to tune to avoid any detonation at all - EVEN if it means that on some cars we dont make quite as much power as the owner wants.

IF you have crappy fuel in your car your power will be crappy also. We can only tune the car till it starts to detonate - after that we back it down quiet a ways to allow a margin of safety. Its a very simple concept actually.

Many of the SUNOCO fuel stations have MULTI blend multiple octane fuel pumps with 89; 91; 93 and 94 octane choices. Some but not all have TWO tank systems which blend in the two gasolines in the proper proportion to get the desired octane. Hence 93 is a mix of 89 and 94. IF you are at a gas station that uses this system and they run out of 94 - then you only have 89 left. They prob should place a sign on the pump at that point saying 89 only - I dont know why that didnt happen but luckily its not my affair.

Guys making posts above saying it cant happen just are proving their own ignorance. People like myself who crave ulimate performance learn the details on how Sunoco works. For the super retarded out there - who just can't "get it" - take a look at the picture of the blending system in the attached link - its at the bottom of the page

http://www.sandrisunoco.com/Sandri/sundesc.htm

"1956 was the year Sun introduced the Custom Blending Pump, a novel system for dispensing a choice of several octane grades of gasoline from a single pump. It revolutionized the method of marketing gasoline, and a model of the pump is on display at the Smithsonian Institution."






We see a huge difference between 93 and 94 octane in how far we can push the tune.

I run 105 octane unleaded on daily basis - $5.45 a gallon - which I can safely push to 24 psi off the spray to 450 whp

 

they ran out of 93 and thus a bad mix occured, um yeah, BS...you heard this from the gas staton or are just making an assumption?


ALL the gas thats in the fuel line would be out and mixed within 2 seconds of turning the car on. These are return fuel systems. Fuel cycles through much much faster then the injectors use it, I would say no more then 5 seconds from in to out.

 

heh... I was waiting for someone else to say this With return fuel systems operating at 3 bar of fuel pressure and pumps flowing upwards of 200lph, there is no such thing as having different gas "in the lines". At least not for very long.

shiv

 

One thing that I have noticed in my car is that when I pump out my 93 octane (you can never get it all) and then dump in some race gas, the first pass I make always gets more knock than the successive passes. And I always tune a little conservatively on the first pass. To be honest, I can't explain it because what shiv said is true, the fuel system pumps gas around so fast that it should mix very quickly.

What may be happening is that the saddle fuel tank that my car has (I think the Evo has one, too) uses the Bernoulli effect to transfer fuel from one side of the tank to the other with the velocity of the fuel in the return line causing the transfer. When you dump fuel into the car, it goes into the side where the pump is. But the fuel that is left on the other side of the tank is still the low octane stuff. It may be that the transfer hose dumps the low octane fuel out right by the pump inlet (I can't remember the geometries involved). Last time I raced at the track, I made sure to run my pump for avout 15 minutes before racing (I have a switch to turn it on) to fully mix the two fuels in the tank.

 

So I guess we'll never know why the car lost 20hp eh? This topic seems to be short on answers aside from the "mis-blending" scenario which I personally can't fathom being true...